A model for low stress cross-diffusional creep and directional coarsening of superalloys
- LTPCM/INPG/UJF, St. Martin d`Heres (France)
- Ecole des Mines, Nancy (France). Lab. de Science et Genie des Materiaux Metalliques
First stages of high temperature creep along <001> in superalloys containing a large volume fraction of the ordered {gamma}{prime} phase are strongly related with directional coarsening (DC), i.e., rafting of {gamma}{prime} precipitates in planes parallel or perpendicular to the stress axis, depending on the signs of lattice misfit and of external loading (tension or compression). The present paper shows that, in the low stresses case, creep cannot directly involve dislocations, and that the major part of the plastic strain during the coarsening process results from a cross diffusion mechanism driven by the gradients of isostatic pressure between phases (Cross-Diffusional Creep). Here, the authors shall consider for the sake of simplicity the case of a superalloy loaded in tension along a <001> direction, with a negative misfit ({delta} = 2({alpha}{sub {gamma}{prime}} {minus} {alpha}{sub {gamma}})/({alpha}{sub {gamma}{prime}} + {alpha}{sub {gamma}}) < 0), which is by far the most frequent situation, and in which the elastic moduli of both phases are comparable.
- OSTI ID:
- 540918
- Journal Information:
- Scripta Materialia, Vol. 37, Issue 5; Other Information: PBD: 1 Sep 1997
- Country of Publication:
- United States
- Language:
- English
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